It has heretofore been proposed to measure the sidewall thickness of a container by placing the container on a mandrel arm with a pivotal head. The mandrel arm is inserted through the open mouth of the container. The head has a tip that internally engages the wall of the container, and is mechanically coupled to a second arm that carries an electronic gauge. The gauge has a tip that externally engages the container wall opposite the point of internal engagement between the head and the inside surface of the container wall. The mechanical coupling between the arms is such that the arms may move up and down in unison to accommodate non-circularity in the container wall as it is manually rotated on the mandrel without affecting the output of the electronic gauge.
Although the container wall thickness measurement technique so described has been employed successfully in the art, further improvements remain desirable. In particular, although the described measurement technique is well suited for measuring sidewall thickness of cylindrical containers, the described technique is not well suited for measuring sidewall thickness of non-cylindrical containers, such as flask-shaped containers that have closely spaced front and back walls and widely spaced sidewalls. It is a general object of the present invention to provide an apparatus for measuring wall thickness of such non-round containers, particularly flask-shaped containers.
The present invention embodies a number of aspects, which may be implemented separately from or more preferably in combination with each other.
Apparatus for measuring wall thickness of a container having an open mouth, in accordance with a first aspect of the present invention, includes a gauge indicator mounted on a support base. The gauge indicator has a first tip for externally engaging the wall of a container and a readout that provides an indication of position of the first tip. A probe arm includes a rod mounted on the base, a second tip pivotally mounted on the rod, a sleeve slidable on the rod, and a link connecting the sleeve to the second tip such that pivotal position of the second tip on the rod is controlled by position of the sleeve along the rod. The second tip is movable between a first position at which a container mouth is receivable over the second tip, and a second position at which the second tip internally engages the wall of the container in opposition to the first tip such that the readout provides a measure of container wall thickness between the first and second tips.
Apparatus in accordance with a second aspect of the present invention for measuring wall thickness of a flask-shaped container includes first and second gauge assemblies. The first gauge assembly includes a first exterior tip for engaging an exterior point on the front or back wall of a flask-shaped container, a first probe arm for insertion through the open mouth of the container and having a first interior tip on the first probe for engaging an interior point on the container front or back wall opposed to the exterior point such that separation between the first tips varies as a function of a first wall thickness between the exterior and interior points, and a first indicator coupled to the first exterior tip for indicating the first wall thickness. The second gauge assembly includes a second exterior tip for engaging a second exterior point on a sidewall of the container, a second probe arm for insertion through the open mouth of the container and having a second interior tip pivotally mounted on the second probe, a control for adjusting angular position of the second interior tip with respect to the axis of the second probe, following insertion of the probe through the container mouth, to engage a second interior point on a container sidewall such that separation between the second tips varies as a function of a second wall thickness between the second exterior and interior points, and a second indicator coupled to the exterior second tip for indicating the second wall thickness.